CHARACTERISTICS AND UTILIZATION OF OLD BLACK WOODPECKER DRYOCOPUS-MARTIUS HOLES BY HOLE-NESTING SPECIES

Old nest holes made by the Black Woodpecker Dryocopus martius were exa mined in two study areas in Sweden. We found a large variation in nest hole characteristics and that the height in the tree and depth of the hole were important factors in the choice of nest hole by secondary h ole nesters. A large proportion of old nest holes remained unoccupied. Many holes were probably of poor quality due to shallow depth, low he ight or narrow entrance. Nest holes in the vicinity of farmland (< 200 m from the field-forest edge) were more often occupied than nest hole s deeper into the forest. This was because Jackdaws Corvus monedula, t he numerically dominant species, only used nest holes near farmland. J ackdaws usually used the best nest holes, while other subordinate spec ies had to use inferior holes near fields or nest holes in areas with less competition, deeper in the forest. Besides birds, some mammals an d bees were found using old Black Woodpecker holes.